Hello all,

Need some advice. As the title states, I have a '96 Disco with 140k miles and I am having idle problems during cold starts, lately, now that it has been getting colder out.

To give you some history, I have done all of the 60k service items listed in this site and the truck runs great otherwise.

The idle problem I have lasts about 30 to 45 seconds with the idle bouncing between 200 and 1200 rpms. When it drops to 200, it almost stalls out, but then the idle immediately bounces back up to 1200. After about 30 to 45 seconds of this "bouncing", it then levels out to 1000 and runs fine from that point forward.

I have yet to do a coolant pressure test, but I am not loosing any coolant and no sweet smell or white smoke from the exhaust. There is also no CEL. Again, the truck runs great, otherwise.

Could this be a sensor issue? Like the throttle position sensor or air intake sensor? This appears to be only an issue when the temp outside is below 55 or so.

Let me know what you think....

 

IACV, MAF cleaning. throttle body cleaning, throttle cables sticking, vac leak (hose cracked), even coolant temp sensor way out of range. Just a few thoughts. Idle seems high, would expect more like 700 when warm.

 

K, I will start with the basics and go from there.

The idle does drop down to the 600-700 rpm range when warm. It hangs around 1000 when it is still cold (first couple of minutes of idling in the driveway).

Thanks for your input.

 

It will idle up a few minutes as it warms up. If you'retalking one or two minutes?????

 

Dirty idle air control valve.

 

Dirty idle air control valve.
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Any do's and don't on cleaning the IACV?

 

Thanks...this is the first thing I will check out. Do I just need to spray it with some carb cleaner?

 

You clean the plunger with carb cleaner and whatever else you need to get rid of the carbon, then do the hole in the manifold where the plunger fits.
As a side note when was it last tuned along with plug wires, have you checked the fuel pressure and do you have any codes if so what are they.

 

I did the full 60k, high mileage tune-up 2 and half months ago. This included plugs, wires, fuel filter, injector cleaner, all fluids/filters changed, u-joints, wheel bearings. After all of that, the truck ran perfect. It is just recently, along with the cold weather, that is started this cold start issue.

No CEL, no codes.

This weekend, I will pull the IACV, clean that and its port in the intake, along with the throttle body. I looked at the throttle body when I performed the full tune up and it looked pretty clean at that time, but might as well take care of that while I am in there.

 

UPDATE: I cleaned the IACV and the Throttle Body and even replaced the PCV hoses. However, I am still having the same issue. Any other ideas?

Again, no CEL, no codes. New spark plugs and wires as of early September. No loss of coolant, no white smoke or sweet smell from exhaust.

The bouncing idle issue lasts only about 30 to 45 seconds (again, goes from about 1000 rmp down to about 250 rmp, then back up again. It does that about 3 or 4 times before leveling out). After that, the truck runs great.

Let me know what you guys think.